Processing method and application of Al-Cu alloy plate with high Cu content

Abstract

The invention discloses a machining method and application of a high-Cu-content Al-Cu alloy plate. The method comprises the following steps that S1, the high-Cu-content Al-Cu alloy plate is subjected to first-time solution treatment and then quenched; s2, the quenched Al-Cu alloy plate with the high Cu content is subjected to cold deformation; s3, the high-Cu-content Al-Cu alloy plate subjected to cold deformation is heated, subjected to overaging treatment and then subjected to cooling, heat preservation treatment and deformation; and S4, the deformed Al-Cu alloy plate with the high Cu content is subjected to secondary solution treatment, quenching and aging treatment. According to the alloy forming method provided by the invention, the impact resistance of the prepared aluminum alloy material is improved. According to the method provided by the invention, a coarse, hard and brittle second phase in the Al-Cu alloy plate with high Cu content can be refined and spheroidized, and meanwhile, fine equiaxed grains can be obtained, so that the strength, plasticity and toughness of the alloy are improved, and the impact resistance is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloys, and in particular to a processing method and application of an Al-Cu alloy plate with a high Cu content. Background Art

[0002] Al-Cu alloy is a typical age-hardening alloy. In practice, the heat treatment state is mostly T87. It is often used as a structural material for high-speed transport equipment such as aircraft, rockets, armored vehicles, etc. Therefore, it is very important to improve its strength and impact resistance. The strength of Al-Cu alloy increases with the increase of Cu content. The maximum solid solubility of Cu element in aluminum matrix is ​​5.65wt%. The undissolved Cu element often exists in the form of coarse, hard and brittle second phases, such as Al2Cu and Al7Cu2Fe. They can induce stress concentration and damage during plastic deformation, and damage the plastic toughness and impact resistance of the alloy. Reducing the size of these second phases and making them spheroidized and more evenly distributed is an effective way to improve the plastic toughness and impact resistance of the alloy.

[0003] On the other hand, grain refinement can improve the strength and plasticity of the alloy at the same time, and is an effective way to improve the impact resistance of the material. In the smelting stage, grain refiners are usually added to the melt to refine the ingot grains. In the forming stage, there are mainly two methods of grain refinement: severe plastic deformation and thermomechanical treatment. Severe plastic deformation (SPD) has a very strong effect of refining grains on polycrystalline materials, and can obtain submicron or even nanometer grains. The SPD method mainly includes equal channel angular extrusion, high pressure torsion, cumulative roll-to-roll welding, etc., but these methods can only prepare small-sized materials at present, with a width or diameter not exceeding 500mm, and the equipment requirements are also high, and the practical application is very limited. Compared with the SPD method, the thermomechanical treatment method has lower requirements on equipment, can produce large-sized plates, and has more applications in actual industrial production.

[0004] In the traditional thermomechanical method for grain refinement currently used, the solute atoms can be dissolved into the matrix through solution treatment to obtain a supersaturated solid solution. In the subsequent over-aging treatment, the unstable supersaturated solid solution is precipitated and grown to obtain high-density (sub) micron-sized second phase particles. Subsequent warm rolling can produce a large number of dislocations around these particles, obtaining high deformation energy storage. During high-temperature short-time recrystallization solution treatment, these positions can stimulate the nucleation of recrystallized grains, increase the nucleation rate of recrystallization, and refine the grains. This method of using precipitated phases to increase the nucleation rate of recrystallization is called particle stimulated nucleation (PSN). In order to achieve a good grain refinement effect, the warm rolling deformation is often required to be more than 80%, but large deformations can easily lead to microcracks or even direct cracking in the plate. To prevent cracking, repeated heating is required during warm rolling to reduce the deformation resistance of the sheet and restore plasticity. Since the length of the sheet increases during warm rolling, the sheet must be cut off before continuing to heat, which increases energy consumption and production time. In order to solve the problem of long production time caused by sheet cracking and repeated heating, a continuous rolling process during warm rolling has been developed. Its characteristic is to increase the initial temperature of warm rolling to avoid repeated heating during warm rolling. However, for Al-Cu alloys with high Cu content, the risk of cracking during sheet rolling increases due to the presence of a large number of coarse, hard and brittle second phases. However, if the warm rolling temperature is increased, the deformation energy storage will be reduced, the PSN effect cannot be fully utilized, and the grain refinement effect is limited. At the same time, increasing the rolling temperature will also promote the growth of the second phase. These second phases are difficult to dissolve into the matrix during the subsequent short-term recrystallization and solid solution. Therefore, it is impossible to re-precipitate uniform, fine and dispersed precipitation phases during the final aging process, thereby failing to further improve the strength and impact resistance of the alloy.

[0005] Therefore, it is necessary to develop a method for efficiently refining grains and second phases for high Cu content Al-Cu alloy sheets. Summary of the invention

[0006] The present invention aims to solve the above-mentioned technical problems existing in the prior art. To this end, the present invention proposes a processing method for a high-Cu content Al-Cu alloy plate, which can refine and spheroidize the coarse hard and brittle second phase in the high-Cu content Al-Cu alloy plate to improve the plastic toughness; at the same time, the grain structure of the plate is refined to improve the strength and plasticity of the alloy. The optimization of the precipitation phase and the grain structure work together to greatly improve the impact resistance of the high-Cu content Al-Cu alloy T87 state plate.

[0007] The invention also proposes the application of the processing method of the Al-Cu alloy plate with high Cu content in the preparation of aerospace components or armor components.

[0008] According to one aspect of the present invention, a method for processing a high Cu content Al-Cu alloy sheet is provided, comprising the following steps:

[0009] S1. The high Cu content Al-Cu alloy sheet is subjected to a first solution treatment and then quenched;

[0010] S2. cold deformation of the quenched high Cu content Al-Cu alloy sheet;

[0011] S3. The cold-deformed high Cu content Al-Cu alloy sheet is subjected to aging treatment, cooling, insulation treatment, and deformation;

[0012] S4. The deformed high Cu content Al-Cu alloy sheet is subjected to a second solution treatment and then quenched and aged;

[0013] In the Al-Cu alloy plate having a high Cu content, 5.5wt.%≤Cu≤7.0wt.%.

[0014] According to the embodiments of the first aspect of the present invention, there are at least the following beneficial effects:

[0015] On the basis of the traditional deformation heat treatment process, the present invention adds a cold deformation step before the over-aging treatment in step S3. On the one hand, the coarse and insoluble primary second phase in the plate can be pre-broken, reducing the stress concentration during subsequent deformation, making the plate less likely to crack. At the same time, a certain amount of dislocation is introduced to increase the number of second phase nuclei and growth driving force during over-aging, prompting the matrix to precipitate more second phases, greatly increasing the recrystallization grain nucleation rate during subsequent solid solution, and then refining the grains. The coarse second phase is broken after the deformation in step S3, and its size becomes smaller. During high-temperature solid solution, it can be promoted to dissolve and spheroidize, thereby increasing the supersaturation of the solid solution. Through the re-aging treatment in step S4, a uniformly dispersed nano-scale strengthening phase can be precipitated in the matrix, which works together with grain refinement to improve the impact resistance of the alloy.

[0016] The method has strong dimensional applicability and can be applied to large-sized plates, and the plates are not prone to cracking during processing; the process is simple, has low requirements on equipment, and is easy to realize industrial production.

[0017] In some embodiments of the present invention, the components of the Al-Cu alloy sheet with high Cu content are: 6.1wt.%≤Cu≤6.6wt.%, trace element content≤0.5wt.%, impurity element Fe≤0.2wt.%, Si≤0.15wt.%, and the balance is Al and unavoidable impurities. Cu is the main added element, and the higher its content, the higher the alloy strength, but too high Cu is not good for the plasticity and toughness of the alloy; trace elements dissolved in the alloy matrix can also play a certain degree of solid solution strengthening effect; impurity elements will harm the performance of the alloy, and their content should be reduced as much as possible.

[0018] In some embodiments of the present invention, the trace elements include Mn, Mg, Ti and Zr.

[0019] In some embodiments of the present invention, in step S1, the temperature of the first solution treatment is 500-540°C.

[0020] The solution temperature within the above temperature range can ensure the rapid dissolution of most of the primary phase, while softening the metal and reducing the resistance to subsequent cold deformation.

[0021] In some embodiments of the present invention, in step S1, the temperature of the first solution treatment is 520-535°C.

[0022] In some embodiments of the present invention, in step S1, the time of the first solution treatment is 1 to 5 hours.

[0023] In some embodiments of the present invention, in step S1, the time of the first solution treatment is 1 to 3 hours.

[0024] In some embodiments of the present invention, in step S2, the cold deformation includes cold rolling deformation, and the deformation amount of the cold deformation is 10% to 50%.

[0025] The deformation amount within the above range helps to control the microstructure of the alloy and prevent the alloy from cracking during deformation.

[0026] In some embodiments of the present invention, in step S2, the cold deformation includes cold rolling deformation, and the deformation amount of the cold deformation is 15% to 45%.

[0027] In some embodiments of the present invention, in step S2, the cold rolling deformation includes multiple passes of cold rolling deformation.

[0028] In some embodiments of the present invention, in step S3, the overaging temperature is 350-450°C.

[0029] The overaging temperature within the above range can promote the formation of a larger number of (sub) micron-sized second phases and give full play to the role of the PSN effect.

[0030] In some embodiments of the present invention, in step S3, the overaging temperature is 400-425°C.

[0031] In some embodiments of the present invention, in step S3, the overaging insulation time is 6 to 30 hours.

[0032] In some embodiments of the present invention, in step S3, the overaging insulation time is 12 to 24 hours.

[0033] In some embodiments of the present invention, in step S3, the temperature after cooling is 200-300°C.

[0034] In some embodiments of the present invention, in step S3, the temperature of the heat preservation treatment is 200-300°C.

[0035] In some embodiments of the present invention, in step S3, the deformation amount of the deformation is 40% to 90%.

[0036] In some embodiments of the present invention, in step S3, the deformation amount of the deformation is 50% to 80%.

[0037] In some embodiments of the present invention, in step S3, the deformation includes warm rolling deformation.

[0038] In some embodiments of the present invention, in step S3, the warm rolling deformation includes multiple passes of warm rolling deformation.

[0039] In some embodiments of the present invention, in step S3, the temperature of the warm rolling deformation is 200-300°C.

[0040] After the over-aging heat preservation is completed, the steel sheet is directly cooled to the warm rolling temperature (the deformation temperature in step S3) without cooling to room temperature and reheating to the warm rolling temperature. During the warm rolling, continuous rolling is adopted without repeated heating and without cutting the plate, thereby reducing energy consumption and production time. The warm rolling temperature is suitable, which can ensure that the rolling can be carried out continuously and the second phase does not grow, and at the same time, high deformation energy storage can be preserved in the alloy.

[0041] In some embodiments of the present invention, the cold deformation amount in step S2 and the deformation amount in step S3 satisfy: 60%≤δc+δw-δc*δw≤90%,

[0042] Among them, δc is the cold deformation amount, which is the initial thickness minus the final thickness of cold deformation and the deformation relative to the initial thickness; δw is the deformation amount, which is the final thickness of cold deformation minus the final thickness of deformation and the deformation relative to the final thickness of cold deformation.

[0043] Under the above relationship of deformation, the risk of rolling cracking of Al-Cu alloy sheet with high Cu content can be avoided by reasonably distributing the deformation; at the same time, under the above relationship of deformation, it is beneficial to crush and spheroidize the coarse, hard and brittle second phase, thereby reducing the stress concentration phenomenon of the sheet and improving the plasticity and toughness of Al-Cu alloy sheet with high Cu content.

[0044] In some embodiments of the present invention, in step S4, the temperature of the second solution treatment is 510-540°C.

[0045] Solution treatment within the above temperature range is beneficial to maximize the dissolution and recrystallization effects of the alloy and optimize the alloy microstructure and impact resistance.

[0046] In some embodiments of the present invention, in step S4, the temperature of the second solution treatment is 520-535°C.

[0047] In some embodiments of the present invention, the second solution treatment is performed for 10 to 60 minutes.

[0048] In some embodiments of the present invention, the second solution treatment is performed for 10 to 30 minutes.

[0049] In some embodiments of the present invention, in step S4, in the heating step, the heating rate of the high Cu content Al-Cu alloy sheet is ≥1°C / s.

[0050] In some embodiments of the present invention, in step S4, the re-aging treatment temperature is 160-170°C.

[0051] The re-aging treatment temperature within the above range is helpful to stabilize the grain structure of the alloy, prevent grain growth, maintain the fine grain state of the alloy, and at the same time can fully precipitate nano-scale strengthening phases to improve the impact resistance of the alloy.

[0052] In some embodiments of the present invention, in step S4, the re-aging holding time is 10 to 24 hours.

[0053] In some embodiments of the present invention, in step S4, the time interval between the quenching step and the re-aging step is no more than 1 hour.

[0054] The above time interval helps to reduce the impact of natural aging and give full play to the effect of re-aging treatment.

[0055] According to a second aspect of the present invention, a method for processing a high-Cu content Al-Cu alloy plate is proposed for use in preparing aerospace components or armor components. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of a flow chart of an embodiment of the present invention;

[0057] Figure 2 The grain structure of the longitudinal section after treatment in Example 1;

[0058] Figure 3 This is the metallographic image of the longitudinal section of the industrially produced Al-Cu alloy T87 state plate with high Cu content;

[0059] Figure 4This is a scanning electron microscope image of the second phase distribution in the industrially produced high-Cu content Al-Cu alloy T87 state plate;

[0060] Figure 5 This is a scanning electron microscope image of the second phase distribution after treatment in Example 1;

[0061] Figure 6 This is the grain structure of the longitudinal section after treatment in Example 2;

[0062] Figure 7 The stress-strain curves of the industrially produced high-Cu content Al-Cu alloy T87 state plate and the high strain rate impact after treatment in Example 2;

[0063] Figure 8 This is a schematic diagram of the process of the conventional thermal deformation treatment in Comparative Example 1;

[0064] Fig. 9 This is the grain structure diagram obtained by conventional thermomechanical treatment in Comparative Example 1;

[0065] Fig.10 This is a scanning electron microscope image of the second phase distribution after traditional deformation heat treatment and re-aging in Comparative Example 1. DETAILED DESCRIPTION

[0066] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0067] Example 1

[0068] This embodiment provides a method for processing a high Cu content Al-Cu alloy plate, which comprises the following steps:

[0069] The Al-Cu alloy sheet with high Cu content has an initial thickness of 20.0 mm, a width of 1800 mm, a length of 2000 mm, and a chemical composition of Cu 6.4 wt.%, Mn 0.25 wt.%, Ti 0.03 wt.%, Fe ≤ 0.20 wt.%, Si ≤ 0.15 wt.%, and the rest is Al and unavoidable impurities;

[0070] S1. Solution quenching treatment is performed on the Al-Cu alloy plate with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace. The temperature is set to 530°C. After the temperature reaches the temperature, the plate is put in. After the temperature stabilizes, the holding time is calculated. The holding time is 3 hours. After the holding period is over, the plate is taken out of the furnace and water quenched immediately.

[0071] S2, cold-rolling the water-quenched plate at room temperature, and the plate thickness is reduced to 17.0 mm after one deformation;

[0072] S3, the plate after cold rolling deformation is subjected to over-aging treatment, wherein the over-aging temperature is set to 400°C, the plate is put into the furnace after the furnace reaches the temperature, and the holding time is calculated after the temperature stabilizes, and the holding time is 24 hours. After the holding is completed, the plate is cooled to 300°C, and the holding is continued at 300°C for 2 hours. After the holding is completed, the plate is taken out of the furnace for continuous warm rolling deformation, and the plate is rolled into a plate with a thickness of 5.1 mm after 5 passes;

[0073] S4. The plate after five passes of rolling is rapidly heated to 535°C for high temperature short-time recrystallization solution treatment. The recrystallization solution is carried out in a salt bath furnace with a holding time of 20 minutes. After the holding is completed, it is immediately quenched in water at room temperature. After about 20 minutes, the recrystallized solution alloy is re-aged to reach the peak aging state. The aging temperature is 170°C and the aging time is 10 hours.

[0074] Table 1 below shows the thickness and deformation of the plate before and after each rolling pass in Example 1, where the cold rolling deformation (δ c ) is the initial thickness minus the final thickness of cold rolling and the deformation relative to the initial thickness; warm rolling deformation (δ w ) is the final thickness of cold rolling minus the final thickness of warm rolling and the deformation relative to the final thickness of cold rolling; the total deformation (δ c +δ w -δ c *δ w ) is the initial thickness minus the final thickness of warm rolling and the deformation relative to the initial thickness. The total deformation of Example 1 is 74.5%.

[0075] Table 1. Thickness and deformation of the plate before and after each rolling pass in Example 1

[0076]

[0077]

[0078] Figure 2 The grain structure of the longitudinal section of the plate of Example 1 after re-aging treatment is fine and evenly distributed equiaxed grains, and the average grain size measured by the intercept method is 18.2 μm.

[0079] Figure 3 This is a metallographic image of the longitudinal section of an industrially produced high-Cu content Al-Cu alloy T87 state plate. The grains are uneven, thick and long, and the average grain size is greater than 150μm.

[0080] Figure 4This is a scanning electron microscope image of the second phase distribution in the industrially produced high-Cu content Al-Cu alloy T87 state plate. The second phase is coarse and unevenly distributed. The large second phase size reaches 12.5μm and the small one is 0.29μm.

[0081] Figure 5 This is a scanning electron microscope image of the second phase distribution of the plate of Example 1 after re-aging treatment. The second phase is distributed relatively evenly, the coarse second phase is fully broken and spheroidized, and the maximum size is only 4.9 μm.

[0082] Example 2

[0083] This embodiment provides a method for processing a high Cu content Al-Cu alloy plate, which comprises the following steps:

[0084] The chemical composition of the plate of the Al-Cu alloy with high Cu content is Cu 6.6wt.%, Mn 0.35wt.%, Ti0.05wt.%, Fe≤0.20wt.%, Si≤0.15wt.%; the rest is Al and unavoidable impurities;

[0085] S1. Solution quenching treatment is performed on the Al-Cu alloy plate with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace. The temperature is set to 535°C. After the temperature reaches the temperature, the plate is placed in the furnace. After the temperature stabilizes, the holding time is calculated. The holding time is 2 hours. After the holding time is over, the plate is taken out of the furnace and water quenched immediately.

[0086] S2, cold rolling the plate after solution treatment at room temperature, the initial thickness of the plate is 20.0 mm, and after two passes of cold rolling, the thickness of the plate is reduced to 14.0 mm;

[0087] S3, the plate after cold deformation is subjected to over-aging treatment, wherein the over-aging temperature is set to 425°C, the plate is put into the furnace after reaching the temperature, and the holding time is calculated after the temperature stabilizes, and the holding time is 12 hours. After the holding is completed, the plate is cooled to 300°C, and is kept at 300°C for 1 hour. After the holding is completed, the plate is taken out of the furnace for continuous warm rolling deformation, and is rolled into a plate with a thickness of 4.2 mm after 5 passes. During the warm rolling, the plate is not returned to the furnace for reheating;

[0088] Table 2 shows the thickness and deformation of the plate before and after rolling in Example 2. The total deformation of Example 2 is 79.0%.

[0089] Table 2. Thickness and deformation of the plate before and after each rolling pass in Example 2

[0090]

[0091] S4. The plate after 5 passes of rolling is quickly heated to 535°C for high-temperature short-time recrystallization solution treatment. The recrystallization solution is carried out in a salt bath furnace with a holding time of 10 minutes. After the holding is completed, it is immediately quenched in water at room temperature and the recrystallized solution alloy is re-aged to reach the peak aging state. The aging temperature is 170°C and the aging time is 12 hours.

[0092] Figure 6 The grain structure of the plate of Example 2 after re-aging is fine and evenly distributed equiaxed grains. The average grain size measured by the intercept method is 16.9 μm.

[0093] Figure 7 The high-speed impact stress-strain curves of the industrially produced high-Cu content Al-Cu alloy T87 state plate and the plate of Example 2 after re-aging. The high-speed impact test was carried out in a separate Hopkinson pressure bar device, and the impact gas pressure was 0.4MPa. The strength and strain of the plate treated by this method are improved compared with those of the industrially produced T87 state plate. The yield strength, peak strength and strain of the T87 state plate are 413MPa, 615MPa and 0.254, respectively, while those of Example 2 are 487MPa, 674MPa and 0.286, respectively. The yield strength and peak strength are increased by 17.9% and 9.6%, respectively. Using the formula The plastic absorption work of the two is calculated separately, where W is the plastic absorption work, σ and ε are stress and strain respectively. The W of the industrially produced T87 state plate is 131.380MJ / m 3 , W of the plate in Example 2 is 154.952 MJ / m 3 , which is 17.9% higher than that of the T87 state plate. The increase in W indicates that the plate can absorb more energy during the impact process, which is beneficial to improving the impact resistance.

[0094] Combination Figures 2 to 7 It can be seen that the treatment method of the present invention can effectively improve the microstructure of industrially produced high-Cu content Al-Cu alloys, transforming them from coarse and uneven long strip grains into fine and uniform equiaxed grains, and reducing the average grain size to below 20 μm; the coarse and unevenly distributed second phase is fully crushed and spheroidized, with a size less than 4.9 μm, thereby improving the high strain rate impact performance of the high-Cu content Al-Cu alloy.

[0095] Example 3

[0096] This embodiment provides a method for processing a high Cu content Al-Cu alloy plate, which comprises the following steps:

[0097] The Al-Cu alloy sheet with high Cu content has an initial thickness of 20.0 mm, a width of 1800 mm, a length of 2000 mm, and a chemical composition of Cu 6.6 wt.%, Mn 0.35 wt.%, Ti 0.05 wt.%, Fe≤0.20 wt.%, Si≤0.15 wt.%; the rest is Al and unavoidable impurities;

[0098] S1. Solution quenching treatment is performed on the Al-Cu alloy plate with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace. The temperature is set to 500°C. After the temperature reaches the temperature, the plate is placed in the furnace. After the temperature stabilizes, the holding time is calculated. The holding time is 2 hours. After the holding period is over, the plate is taken out of the furnace and water quenched immediately.

[0099] S2, cold rolling the plate after solution treatment at room temperature, the initial thickness of the plate is 20.0 mm, and after two passes of cold rolling, the thickness of the plate is reduced to 14.0 mm;

[0100] S3, the plate after cold deformation is subjected to over-aging treatment, wherein the over-aging temperature is set to 350°C, the plate is put into the furnace after reaching the temperature, and the holding time is calculated after the temperature stabilizes, and the holding time is 12 hours. After the holding is completed, the plate is cooled to 300°C, and is kept at 300°C for 1 hour. After the holding is completed, the plate is taken out of the furnace for continuous warm rolling deformation, and is rolled into a plate with a thickness of 4.2 mm after 5 passes. During the warm rolling, the plate is not returned to the furnace for reheating;

[0101] S4. Rapidly heat the plate after 5 passes of rolling to 510°C for high-temperature short-time recrystallization solution treatment. The recrystallization solution is carried out in a salt bath furnace with a holding time of 10 minutes. After the holding is completed, immediately water quench at room temperature and the recrystallized solution alloy is re-aged to reach the peak aging state. The aging temperature is 170°C and the aging time is 12 hours.

[0102] Example 4

[0103] This embodiment provides a method for processing an Al-Cu alloy with a high Cu content. The difference between this embodiment and Embodiment 1 is that in step S3, the alloy is rolled into a plate with a thickness of 8.5 mm through 5 passes, and the other conditions are the same.

[0104] Comparative Example 1

[0105] This comparative example provides a traditional thermomechanical treatment method for refining grains of Al-Cu alloy plates with high Cu content. The treatment method in this comparative example is S1 solid solution quenching treatment, S2 overaging treatment, S3 rolling warm deformation, S4 high temperature short-time recrystallization solid solution, and no cold rolling deformation. Figure 8 As shown, the specific steps are as follows:

[0106] The chemical composition of the plate of the Al-Cu alloy with high Cu content is Cu 6.4wt.%, Mn 0.25wt.%, Ti0.03wt.%, Fe≤0.20wt.%, Si≤0.15wt.%, and the rest is Al and unavoidable impurities.

[0107] S1. Solution quenching treatment is performed on the Al-Cu alloy plate with high Cu content. The solution treatment is carried out in an air atmosphere resistance furnace. The temperature is set to 535°C. After the temperature reaches the temperature, the plate is put in. After the temperature stabilizes, the holding time is calculated. The holding time is 2h. After the holding is completed, the plate is taken out of the furnace and water quenched immediately;

[0108] S2. Perform over-aging treatment on the plate after solid solution treatment, wherein the over-aging temperature is set to 425°C; put the plate into the furnace after it reaches the temperature, and start calculating the insulation time after the temperature stabilizes; the insulation time is 12h, and the plate is taken out of the furnace and air-cooled after the insulation is completed.

[0109] S3, the over-aged plate is heated to 300℃ with the furnace, and kept warm for 2h after reaching the set temperature; after the plate is kept warm, it is taken out of the furnace for rolling. The initial thickness of the plate is 20.0mm, and the thickness is reduced to 4.2mm after 6 rolling passes. Table 3 shows the thickness and deformation of the plate before and after rolling in Comparative Example 1. The warm rolling deformation, i.e. the total deformation, of the comparative example is 75.0%. Since the edge of the plate cracks when it is rolled to the 5th pass, in order to ensure the safe rolling, the cracked part of the plate is cut off, and the plate is cut longitudinally and returned to the furnace for heating and heat preservation to reduce the deformation resistance. The heat preservation temperature is 300℃, and the heat preservation time is 1 to 2h. After the heat preservation is completed, the cut plates are taken out one by one and continue to be rolled.

[0110] S4. The deformed plate is quickly heated to 535°C for high temperature short-time recrystallization solution treatment. The recrystallization solution treatment is carried out in a salt bath furnace with a holding time of 10 minutes; after the holding time is completed, the plate is immediately quenched in water at room temperature.

[0111] Table 3. Thickness and deformation of the plate before and after rolling in Comparative Example 1

[0112]

[0113] Figure 8 This is a schematic diagram of the process of the conventional thermal deformation treatment in Comparative Example 1;

[0114] Fig. 9 This is the grain structure of the plate in the comparative example after recrystallization and solid solution. The average grain size measured by the intercept method is 26.7μm.

[0115] Fig.10This is a scanning electron microscope image of the second phase of the plate in Comparative Example 1 after traditional deformation heat treatment and aging at 170°C for 12 hours. The coarse second phase still exists and has not been spheroidized.

[0116] It can be seen from the embodiments and comparative example 1 that the grain refining method of the present invention has a more significant grain refining effect than the traditional deformation heat treatment, and can improve the morphology of the coarse second phase, reduce its size and spheroidize it, thereby improving the impact resistance of the Al-Cu alloy sheet with a high Cu content; at the same time, the warm rolling process can be carried out continuously without secondary heating and cutting of the sheet, thereby reducing energy consumption and production time.

[0117] Comparative Example 2

[0118] This comparative example provides a traditional thermomechanical treatment method for refining grains of Al-Cu alloy plates with high Cu content, specifically:

[0119] The chemical composition of the high Cu content Al-Cu alloy plate is Cu 6.4wt.%, Mn 0.25wt.%, Ti0.03wt.%, Fe≤0.20wt.%, Si≤0.15wt.%, and the rest is Al and unavoidable impurities;

[0120] The high Cu content Al-Cu alloy plate was solution treated at 475℃ / 1.5h and water quenched at room temperature. The solution state plate was cold rolled by 50% to 10.0mm. The 10.0mm plate was kept at 400℃ for 30min and then continuously deformed by 70% without returning to the furnace during the continuous deformation process. The final rolled plate was treated at 480℃ / 0.5h and 120℃ / 24h.

[0121] Test example

[0122] The performance of the embodiments and comparative examples is shown in Table 4:

[0123] Impact resistance test standard: GB / T 34108-2017;

[0124] Table 4. Impact resistance test data of examples and comparative examples

[0125]

[0126] The high Cu content Al-Cu alloy sheet prepared by the present invention has significantly improved impact strength and plastic absorption work compared with the industrially produced T87 state sheet. Although the comparative example 1 using the traditional deformation heat treatment method has improved the strength and plastic absorption work relative to the T87 state sheet, the improvement is not obvious. In comparative example 2, the solid solution temperature was lowered, the second phase failed to dissolve into the matrix, and it was impossible to re-precipitate a uniform, fine and dispersed precipitate phase during the final aging process. In addition, the originally existing fine precipitate phase will coarsen and grow during the 400°C insulation process, resulting in its strength and plastic absorption work not only not being improved relative to the T87 state sheet, but also showing a significant decrease.

[0127] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for processing a high Cu content Al-Cu alloy sheet, characterized in that: The following steps are involved: S1. The high Cu content Al-Cu alloy plate is subjected to a first solution treatment and then quenched; S2. cold deformation of the quenched high Cu content Al-Cu alloy sheet; S3. The cold-deformed Al-Cu alloy sheet with high Cu content is heated and aged, then cooled, heat-insulated and deformed; S4. The deformed high Cu content Al-Cu alloy sheet is subjected to a second solution treatment and then quenched and aged; In the Al-Cu alloy plate having a high Cu content, 5.5wt.%≤Cu≤7.0wt.%.

2. The processing method of the high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: The temperature of the first solution treatment is 500-540° C.; and / or the time of the first solution treatment is 1-5 hours.

3. The processing method of the high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S2, the cold deformation includes cold rolling deformation, and the deformation amount of the cold deformation is 10% to 50%.

4. The method for processing a high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S3, the over-aging temperature is 350-450° C.; and / or the over-aging holding time is 6-30 hours.

5. The processing method of the high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S3, the temperature after cooling is 200-300°C.

6. The method for processing a high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S3, the temperature of the heat preservation treatment is 200-300°C.

7. The processing method of the high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S3, the deformation amount of the deformation is 40% to 90%; And / or, the cold deformation amount in step S2 and the deformation amount in step S3 satisfy: 60%≤δc+δw-δc*δw≤90%, wherein δc is the cold deformation amount, which is the deformation amount of the initial thickness of the plate minus the final thickness of the cold deformation relative to the initial thickness; δw is the deformation amount, which is the deformation amount of the final thickness of the cold deformation minus the final thickness of the deformation relative to the final thickness of the cold deformation.

8. The method for processing a high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: In step S4, the temperature of the second solution treatment is 510-540° C.; and / or the time of the second solution treatment is 10 min-60 min.

9. The method for processing a high Cu content Al-Cu alloy sheet according to claim 1, characterized in that: The re-aging temperature is 150-180° C.; and / or the re-aging holding time is 8-120 h.

10. Use of the processing method of a high Cu content Al-Cu alloy plate according to any one of claims 1 to 9 in the preparation of aerospace components or armor components.

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